1. Field
This document relates to an image display device capable of improving a display quality.
2. Related Art
Based on the progress of a variety of image processing techniques, there has been recently developed an image display device capable of selectively implementing two-dimensional images (hereinafter, referred to as “2D images”) and three-dimensional stereoscopic images (hereinafter, referred to as “3D images”).
As methods of implementing 3D images in the image display device, there are known a stereoscopic technique and an autostereoscopic technique.
The stereoscopic technique uses binocular parallax images which are great in the stereoscopic effect. The stereoscopic technique has a type of using glasses and a type of not using glasses, and, at present, the two types have been put into practical use. In the type of not using glasses, the stereoscopic images are implemented by dividing optical axes of binocular parallax images, by using optical plates such as parallax barriers provided at front and rear surfaces of a display panel. In the type of using glasses (hereinafter, referred to as a “glasses type”), binocular parallax images are displayed on a direct view display panel or a projector by changing polarization directions or in the temporal division manner, and polarization glasses or liquid crystal shutter glasses are used to implement stereoscopic images.
The glasses type is greatly classified into a first polarization filter type using a pattern retarder film and polarization glasses, a second polarization filter type using a switching liquid crystal layer and polarization glasses, and a liquid crystal shutter glasses type. The first and second polarization filter types have a low transmittance of 3D images due to the pattern retarder film or the switching liquid crystal layer which functions as a polarization filter and formed in a liquid crystal display panel.
The liquid crystal shutter glasses type implements 3D images by alternately displaying a left eye image and a right image on a display device by the frame unit, and opening and closing the left and right eye shutters of the liquid crystal shutter glasses in synchronization with the display timing. In the liquid crystal shutter glasses, only the left eye shutter is opened for the frame period when the left eye image is displayed, and only the right eye shutter is opened for the frame period when the right eye image is displayed, thereby generating the binocular parallax in a temporal division manner.
In order to selectively implement 3D images and 2D images, the latest image display device mainly employs a hold type display device such as a liquid crystal display (“LCD”). The LCD maintains data which has been charged for the previous frame period due to the response time of the liquid crystal, till new data is written therein. When 3D images are implemented by the image display device, due to the response time delay characteristic of the liquid crystal, 3D crosstalk of a ghost pattern can be viewed for a time when the left eye image is changed to the right eye image or the right eye image is changed to the left eye image. A principle by which the 3D crosstalk is viewed will be described in outline.
If it is assumed that the left eye shutter of the liquid crystal shutter glasses is opened for the n-th frame period and the right eye shutter of the liquid crystal shutter glasses is opened for the (n+1)-th frame, in the LCD, left eye image data is sequentially addressed for the n-th frame period and right eye image data is sequentially addressed for the (n+1)-th frame period. When the left eye shutter of the liquid crystal shutter glasses is being opened, a portion of pixels (pixels placed in the lower part of the panel, which lies in the latter addressing order) where the left eye image data for the n-th frame has not been written yet maintains the right eye image data which has already been written for the (n−1)-th frame period. Therefore, a viewer's left eye views a portion of the right eye image for the (n−1)-th frame along with the left eye image for the n-th frame in an overlapping manner. In addition, when the right eye shutter of the liquid crystal shutter glasses is being opened, a portion of pixels (pixels placed in the lower part of the panel, which lies in the latter addressing order) where the left eye image data for the (n+1)-th frame has not been written yet maintains the left eye image data which has already been written for the n-th frame period. Therefore, a viewer's right eye views a portion of the left eye image for the n-th frame along with the right eye image for the (n+1)-th frame in an overlapping manner.
In addition, when 2D moving pictures are implemented by the image display device, due to the maintaining characteristic of the liquid crystal, there may be occurrence of a motion blurring that a screen is not clear and appears blurred. In order to remove the motion blurring, it is necessary to improve a moving picture response time (“MPRT”).